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JE Labs Simple 46

I've been hoarding type 46 power tubes gathered from radio shows I attended with my buddy Chong in the late 90s. Building an SE 46 amp was in my to do list when I packed up for Manila in '08. But things got in the way. Finally, after a round trip across the Pacific, the amp has come into fruition.

Given its designation, one would think that it is just a 45 with dual grids. However, aside from the UX-5 tube base requirement, the 46 is notquite a 45. It only puts out 1250 mWatts, 750 mWs less than the 45's 2000 mWs. Maximum plate dissipation with grid 2 tied to the plate is 5.5W compared to 10W for the 45. Although it will perform very well loaded with a 5k primary Z output transformer, the textbook recommended load is closer to 7k, due to its higher plate resistance of 2380 ohms vs. 1700 ohms for the 45.



It's been over 20 years since the Simple 45/2A3 was uploaded to the now defunct DIY section of the old Angela Instruments website. So I wanted to reprise that old-scho…
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Cinestill Cs-41 Color Film Developing Kit

Intrigued by an e-newsletter from Freestyle Photographic Supplies, I ordered this color film processing kit, which promised to be just as straightforward as developing B&W film.

Mixing the Chemicals
Developer = 20 oz of distilled water heated to 120° F + Parts A, B & C to make 1 quart

Blix (Bleach/Fixer) = 18 oz of distilled water heated to 125° F + Parts A, B & C to make 1 quart

Preparation
As suggested by the Cs41 website, I got a $25 foot spa from Walmart as a tempering bath for the chemicals and the developing tank.

Temperature is most critical with the developer. Since the foot spa is just a tempering bath and does not heat up water, I filled it up with hot water from the tap, which was between 105-110°F.

Meanwhile, I filled up a pot with hot water from the tap and heated up the developer in this water bath on the stove to my chosen 102° F developing temperature.
Pre-wash
 I did a pre-wash to stabilize developing tank temperature at 102°F. Developing

The developer is…

Shure Mic Transformers

Tipped off by my buddy, Ben C (dude in the middle), I scoured eBay for Shure Mic transformers that can be repurposed for MC step-up duty. These transformers typically sell for under $50/pair shipped within the USA.

They don't have model numbers so I'll identify them based on their step-up ratio.


Primary DCR = 35 ohms and 3500 ohms in the secondary.  I measured a step up ratio of about 1:17, which suits the Denon DL103 and DL103R well. It can be a pinch hitter for the Ortofon SPU in my system, but ideally more gain is needed.

This unit has slightly less gain at about 1:12, primary DCR = 20 ohms and secondary = 2000 ohms. What it gives up in gain is made up for by slightly wider bandwidth. If I were to split hairs, I'd pick this over the 1:17 model above if I were using a DL103 exclusively.


The tonal balance of both Shure transformers is actually quite similar to the Altec 4722 with just a touch less transparency and authority throughout the audio band. At their present ask…

Octal EAR 834P phono preamp

During my visit to NYC earlier this summer, my buddy Ding loaned me his home-brewed octal version of the EAR 834P phono preamp using 3 x 6SL7 octal tubes. Powering the preamp is a General Radio 1201-B tube regulated power supply.

Ding is not into boutique parts. Instead, he used carbon film resistors, mylar coupling capacitors and electrolytic caps gathered from Hamfests and surplus stores. Proper grounding and parts placement ensured a very quiet phono stage.

Traditional tube phono stages like the classic Dyna PAS 3 and Marantz 7 employed active RIAA EQ networks inserted in the negative feedback loop from the final stage to the input stage. In the 834P, Tim de Paravicini used active RIAA EQ with a clever twist - theEQ network is fed from the cathode follower output back to the second stage only. IMO, the benefits of this topology are: a 1st stage unimpeded by negative feedback, low noise and low output impedance.

I've been enjoying this phono stage so much that I'm inspired …

Lens Filter Ring Vise

I recently fixed two lenses from my collection which had dented filter rings using this $36 tool from Micro-Tools.

The tool didn't come with instructions but using it is pretty straightforward. As a precaution, I covered the front element with cardboard. First, I positioned the moving jaw of the tool on the dent and aligned the threads from the jaws of the tool to mate with the threads of the filter ring. Then I gently spread out the jaws of the tool to press out the dent. I cannot over emphasize going slowly but surely!




The tool has paid for itself ;)

Noguchi Finemet: FM-3WS-H + FM-6WS output transformers

This was the last extensive testing and listening session I did in the attic before the stereo and mono systems were rescaled. I misplaced some data and just recovered them recently. So as promised in a previous blog entry, here's the write-up on the two entry-level SE Finemet OPTs from Noguchi.

WARNINGThese are bonsai-sized output transformers. If thumping bass frequencies is your idea of high-fidelity you should stop here right now. Otherwise, please proceed with caution ;)
Noguchi FM-3WS-H
David vs. Goliath - indeed, the FM-3WS-H is tiny. I had to mount it on a perf board so that it wouldn't fall from the square mounting hole left by the Tamura F7004 ;)


Technical and listening tests were done with the output transformer mounted in the SE10/VT25 amp, which resides in the attic mono system.
Noguchi FM-6WS
The FM-6WS is not that much bigger either.


Technical and listening tests were done with the output transformer mounted in the Radiotron SE2A3 stereo amp in place of a pair o…